This DLL allows you to open and duplicate any type of asset (including cooked and generated class assets) in UEFN, regardless of whether or not you use the No Valkyrie Plugin Pak.
You must be logged in Github, go to the Actions tab, select the latest workflow (item), if you scroll down you should find UEFN Unlocker inside the Artifacts category, click it and it will start downloading.
There are a lot of ways to inject a DLL into a program, for example Process Hacker (the one that I use), Cheat Engine, etc... Just search a tutorial in the internet.